This paper describes experiments and numerical modeling of a lean premixed, atmospheric pressure (phi = 0.55) hydrogen-ethane-air flat flame with 1.5 mol % of CF3CHFCF3, Stable species concentrations as a function of height above the burner were obtained by sampling with a water-cooled quartz probe; these gases were subsequently analyzed by infrared spectroscopy. Numerical modeling of this flame was performed with a detailed chemical kinetic mechanism. Discrepancies between modeled and experimental concentrations were attributed to external probe-induced distortions. A phenomenological treatment of the external distortion gave reasonable agreement for all species. Plug-flow calculations were performed to determine the extent of sample composition change within the probe. These showed that homogeneous gas-phase reactions did not cause any changes to the sample. A surface oxidation channel was included to simulate CO loss. Reaction flux analyses revealed that flame inhibition arises from H- and O-atom, and to a lesser extent CH3 radical, consumption by the fluorinated fragments CF3, CF2, and CFO. Consumption of OH radicals appeared to be relatively inefficient. A concentration sensitivity analysis on the species CO and CF2O was performed to show that reactions between CFB radicals and the major flame radicals were sensitive. The concentrations of these species were only mildly sensitive to reactions involving larger fluorinated species.